1. Field
The present invention relates to an information recording and reproducing unit for recording information into a disc-like recording medium and reproducing information from the recording medium, and a circuit unit for use therein.
2. Description of the Related Art
In recent years, a magnetic disk unit (HDD) and an information recording and reproducing unit (disk unit) which uses an optical disk unit or the like as its recording medium have been widely used as an external recording unit for a computer or an image recording unit.
For example, a magnetic disk unit has a magnetic disk as a magnetic recording medium, a recording and reproducing head for writing information into the magnetic disk and reading out information from the magnetic disk, a carriage for moving the recording and reproducing head to an arbitrary position in the radial direction of the magnetic disk, a drive unit for moving the carriage and a drive circuit for supplying control signals corresponding to an amount for moving the carriage to the drive unit, these components being accommodated in a rectangular casing.
Recently, a further reduction in size has been accelerated in a magnetic disk unit in order to use this magnetic disk unit as a recording device for various kinds of electronic appliances, particularly, smaller electronic appliances. For example, in a magnetic disk unit of 1 inch or more in the diameter of disk, printed circuit boards to be disposed on the surface of its casing such that they overlap can be reduced to be smaller than the area of the casing surface.
However, in the magnetic disk unit of less than 1 inch in diameter of disk, its printed circuit board needs to be reduced in size in accordance with a reduction in size of its casing. Thus, an installation space on the printed circuit board is reduced so that it becomes difficult to mount a plurality of electronic parts.
For the reason, a method of overlapping a printed circuit board by folding at a predetermined position has been proposed.
Meanwhile, Jpn. Pat. Appln. KOKAI Publication No. 11-249215 describes a proposal for preventing components mounted on a circuit board from contacting each other when the printed circuit board is overlapped by folding back.
However, when a flat cable for use in electrical connection to other parts connected to the printed circuit board is deformed in accordance with displacement of a control object, it is demanded that components within the printed circuit board do not make contact with each other and the flat cable does not affect the displacement of the control object. There is no description relating to a flat cable or a displacement of the control object in the aforementioned publication.